共查询到16条相似文献,搜索用时 62 毫秒
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IP 组播技术是一种可以把单个数据信息同时分发到不同的用户去的网络技术。卫星网络固有的广播信道特性使得它很适合组播应用。然而目前针对卫星网络的可靠组播服务研究很少,虽然已经有一些关于地面Internet组播协议建议,但他们并不适合于卫星网络。在卫星网络组播传输中的一个关键技术是传输协议设计。该文提出一种基于Agent的宽带卫星网络可靠组播传输协议(ASMTP)。该协议利用接收端Agent来实现卫星组播,采用分组级FEC和本地差错恢复纠正传播中的非相关错误和相关错误。在ASMTP中,还实现了流量控制和拥塞控制机制。仿真结果表明,在卫星网络环境中,ASMTP性能优于MFTP(Multicast File Transport Protocol),同时具有较好的网络可扩展性。 相似文献
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本文根据MANET的运用场景和特点,参考CFDP文件传送协议,提出一种简单、可靠而又实用的无线网络文件传送协议。采用文件传送事务的思想和分段传送、RS纠错编码、NAK延迟传送的方案,以简化软件设计。同时给出协议实现的具体步骤、报文结构和模块组成,并对定时器定时设置和组成、预期传送时间等进行了数学分析。 相似文献
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卫星网络中基于UDP的可靠数据传输协议 总被引:1,自引:0,他引:1
在卫星网络中,标准的传输控制协议TCP不能充分发挥网络的性能。论文通过分析卫星网络的特点提出了一个基于UDP的应用层传输协议UDT-Sat。该协议使用基于带宽估计的拥塞控制和基于选择性负向确认的快速重传机制实现数据高效可靠的传输。实验表明,UDT-Sat在卫星网络中具有很高的带宽利用率,同时保持了良好的公平性和稳定性。 相似文献
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Sinha Prasun Nandagopal Thyagarajan Venkitaraman Narayanan Sivakumar Raghupathy Bharghavan Vaduvur 《Wireless Networks》2002,8(2-3):301-316
Wireless wide-area networks (WWANs) are characterized by very low and variable bandwidths, very high and variable delays, significant non-congestion related losses, asymmetric uplink and downlink channels, and occasional blackouts. Additionally, the majority of the latency in a WWAN connection is incurred over the wireless link. Under such operating conditions, most contemporary wireless TCP algorithms do not perform very well. In this paper, we present WTCP, a reliable transport protocol that addresses rate control and reliability over commercial WWAN networks such as CDPD. WTCP is rate-based, uses only end-to-end mechanisms, performs rate control at the receiver, and uses inter-packet delays as the primary metric for rate control. We have implemented and evaluated WTCP over the CDPD network, and also simulated it in the ns-2 simulator. Our results indicate that WTCP can improve on the performance of comparable algorithms such as TCP-NewReno, TCP-Vegas, and Snoop-TCP by between 20% to 200% for typical operating conditions. 相似文献
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As a prevalent reliable transport protocol in the Internet, TCP uses two key functions: AIMD (Additive Increase Multiplicative Decrease) congestion control and cumulative ACK technique to guarantee delivery. However, with these two functions, TCP becomes lowly efficient in ad hoc networks that have a much lower BDP and frequent packet losses due to various reasons, since TCP adjusts its transmission window based on packet losses. In this paper, we present that, provided that the BDP is very small, any AIMD-style congestion control is costly and hence not necessary for ad hoc networks. On the contrary, a technique to guarantee reliable transmission and to recover packet losses plays a more critical role in the design of a transport protocol over ad hoc networks. With this basis, we propose a novel and effective datagram-oriented end-to-end reliable transport protocol for ad hoc networks, which we call DTPA. The proposed scheme incorporates a fixed-size window based flow control and a cumulative bit-vector based selective ACK strategy. A mathematical model is developed to evaluate the performance of DTPA and to determine the optimum transmission window used in DTPA. The protocol is verified using GloMoSim. The simulation results show that our proposal substantially improves the network performance. 相似文献
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战术通信网需要多播技术以支持多种组播应用,如情形感知、任务协作等。无线通信可为战术通信网组播通信提供支持,但其可靠性不高,不能直接应用,必须加以控制。为此,研究了一种利用IP多播路由和转发服务提供端到端可靠数据传输协议,即面向否定确认的可靠多播协议(NORM)。深入分析了NORM协议的反馈确认、拥塞控制、包级FEC等关键技术。在结论与展望中,提出了这一领域的难点和对今后工作的展望。 相似文献